A syringe is conventionally used for administering a medical fluid or a medicine (referred to as a medical fluid, hereinafter) that cannot be administered orally. However, a method using a syringe provides a large degree of stress and pain to a patient. Another method is also used for transdermal administration by using a medical patch which contains a medical fluid; however, this method has a problem of requiring an extended period of time until the medicine takes effect and of limiting the kind of medical fluids usable.
In order to solve the problems mentioned above, medical fluid administration techniques have been developed involving microneedles and microblades.
A medical fluid administering method using a microneedle (Japanese Laid-Open Publication No. 2006-149818, Reference 1) is used for the purpose of reducing the time until the effect of the medicine appears by administering a medical fluid directly to a live cell layer (epidermis below the prickle cell layer) of the cuticle. The method is also used for the purpose of reducing the time until the effect of the medicine, such as insulin or an anesthetic, appears and a time until the effect of a physiological active substance, such as DNA, RNA, protein and peptide, appears, with a similar principle.
The microneedle is a microscopic needle with generally a tip of 10 μm in diameter, 100 μm in height, and with a base of 100 μm in diameter. The microneedle is a micro structure with a large aspect ratio. Therefore the medical fluid administering method using a microneedle has the advantage of not causing pain upon inserting it into a human body because the microneedle does not reach a pain spot since it only penetrates the stratum corneum of the skin.